Central-battery telephone system.



No.' 657,338.1 l Patented sept. 4, |900.'

w. w. DEAN. CENTRAL BATTEBY TELEPHONE SYSTEM.

(Application 'led Apr. 28, 1899.)

@No Mandel.)

UNITED STATESV PATENT OFFICE.

WILLIAM W. DEAN, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE KELLOGG SWITCH BOARD AND SUPPLY COMPANY, OF SAME PLACE.

CENTRAL-BATTERYV TELEPHONE SYSTEM.

SPECIFICATION forming` part of Letters Patent No. 657,338, dated September 4, 1900.

Application filed April 28| 1899.

To all whom it maf/y concern:

Be it known that I, WILLIAM W. DEAN, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented a certain new and useful Improvement in Central-Battery Telephone Systems, of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawings, forming a part of this specification.

My invention relates to a central-battery telephone system, my object being to provide a system whereby a common batteryl or source of charging-current at the central sta- 'tion may be connected in circuit with the telephone-line to charge the microphone or talking circuit at the substation, whereby the separate batteries or sources of electricity at the substation may be dispensed with.

In accordance with my invention I provide a plurality of telephonelines, each having two limbs to constitute a metallic talkingcircuit, each line being connected or associated at the substation with a third conductor, which may be the ground or other suitable conductor, and at the central station I provide a common battery or source of electricity connected with the devices thereat employed for uniting the telephone-lines in talking-circuit, the said source of electricity being arranged to be connected in a circuit including in series said third conductor and the two telephone-lines, whereby the source of electricity will send current over the said circuit to charge the microphone-circuit. I preferably employ in the said circuit a microphone and the primary of an inductioncoil, said microphone and primary being included in parallel paths of the circuit, while the secondary of the induction-coil is connected between the two limbs of the metallic circuit. I preferably unite the lines at the central station through repeatingcoils,where by each line Vforms a separate and distinct circuit for the talking-currents. The source of electricity will be connected between the telephone -lines at the central station and is preferably connected between the electrical centers of the windings of the repeato ing-coils. The current from the source of electricity may traverse the two limbs of each Serial No. 714,870. No model.)

line in parallel; or one limb of each line may be alone employed for the passage of the charging-current. In order to preventthe variations of current upon one pair of connected lines from interfering with any other pair connected with the common source of current, I employ a resistance, preferably a reactive or impedance coil, interposed between the source of electricity and each of the connected telephone-lines. In this Inanner the variation of current upon any connected pair of lines is prevented from aifecting any other pair of connected telephonelines.

I have illustrated my invention in the accompanying drawings, in which- Figure l is a diagram illustrating my invention. Fig. 2 is a diagram illustrating the manner of connecting the common battery with a plurality of pairs of telephone-lines.

Like letters refer to like parts in both iigures.

The telephone-line extends in two limbs u. ct from the substation uto the central station, and the telephone-hook b is interposed in one of the limbs af and is adapted to rest against a back contact when the receiver is removed froml t-he hook, and a contact b', controlled by the telephone-hook, is adapt-ed to engage a contact b3 to close limb ct during conversation. At the substation the limbs a and a are connected, respectively, with the impe- "dance and balancing coils c and c', and from the electrical center of these coils extends the leg e2, in which is connected the transmittercircuit, which in the present instance is illustrated as consisting of a microphone c3 in one of two parallel paths and the primary c4 of an induction-coil in the other path. The secon'clary c5 0f the induction-coil is connected between the limbs aand a and also includes the receiver c6. At the central station the limbs ct and e' terminate in the line springs or contacts d d of the switch-socket. The individual annunciator d2 is connected between the contact d3 and the pole of the chargingbattery t', so that the insertion of the plug disconnects the individual annunciator in the usual manner. The connecting-plugs at the central station are provided with contacts e e' and e2 e3, respectively, whereby two telephone- IOO lines lmay be united together for conversation.. Interposed in the cord-circuit are the windings ff and f2 f3 of the repeating coils, and from the electrical center of the coils ff" a conductor g extends to one poleof the battery i and contains the clearing-out annunciator h, while from, the electrical center of the windings]02 f3 a conductor g extends tov phone-lines whereby the batterytmay be utili ized for a pluralityof pairs of connected telephone-lines. 'lhe apparatus and circuits of l the substations A and B are similar an'd have been indicated by the corresponding refer-v ence-letters.

-The apparatus for sending signals from the central station to the substation may be-of any of the usual forms and for clearnessl has been omitted.

that the charging-current from the battery t' may traverse only one of the two limbs of .the When it is desired' to utilize both limbs of the talking-circuit for' the charging-current, the condensers may be metallic talking-circuit.

omitted.

circuit with the battery t'.

upon for calling-cu rrents.

f, annunciator h, battery vl, annunciator h', coil f2, and thence over limb la of subscriber B to ground. The charging-battery?.` is .thus connected in series with the two connectedl telephone-lines and serves to charge the mi- 1 crophope-circuit of the two subscribers. The variations of the resistance ofthe microphone at either subst-ation causes a varying current to liow through the primary of the inductioncoil thereat, whichl induces a current in the secondary coil. Thus the inducedcurrent over the two metallic limbsot' the telephoneline, while the charging-current passes over the two telephone-lines in series and returns through ground or other common return.

When the subscribers are through con versation, thehanging up of the telephone-receiver opens the limb d, and thereby stops the tlow of current throughannunciator h, which causes a signal to indicate that the subscribers desire disconnection.

vTheclearing-out annunciators h h should have sufficient retardation or impedance to prevent the fluctuation of current in any pair of connected telephone-lines from affecting any other pair of connected lines. I Instead of u j employing the coils of clearing-out annun- I have illustrated in dotted lines condensf ers k lo', inserted in the windings of the re- V,peating-coils at the central station in order and D, are illustrated, the lines A B being connected together to form one pair of connected lines, while t-he lines C and D are connected together toform another pair of connected lines. It will be noted that the comp .mon battery t is arranged to supply charging- Supposing subscriber A desirous of conversation, he removes his telephone-receiverj from the hook b, thus closing the metallic. limbs and closes the circuit from ground at the substation through the microphone-cir-f cuit, conductor c2, limb a, contactI d3, annun- .ciator d2, and battery@l to ground, which will` be provided by any telephone-lines which are 5 connected for conversation and which are inry Since more or less of the telephone-lines are continuously in cirl cuit, the ground. thus produced may be relied Other methods ot signaling the central station may, however, `be employed when desired. The operator in- 1 serts the calling-plug in the socket of sub-g scriber A and insertsthe opposite plug of the. pair in the socket of subscriber B, and afteri subscriber Bresponds and removes his telephone from its hook the two subscribers are connected together for conversation. As thus 1 connected, the circuit of battery vl maybe; traced from ground at substation A through: conductor c2, limb a, spring d, sleeve e, coil;

current to the two pairs of connected lines and the two pairs are in parallel with each other. Likewise any greater'number of pairs of connected lines may'beconnected in circuit with the same battery, and the circuit arrangements and the presence of the impedance-coils h h h2 h3 prevent the currents of one pair of lines from interfering with those of another. VItwill be observed that a plurality of cord connectors are associated with acommon battery, one terminal ol" each cord connector being joined to one pole of the battery, while the other terminalof the cord connector Ais joined to the other pole of the battery.

In the appended claims I have referred to 'a source of electricity asv ad apted to send current overa circuit includingin series the third conductor and the two connected telephonelines, and it will be understood thatthe said .series circuit may include only one limb of Veach telephone-line or may include the two limbs Vof each telephone-line, the two limbs sis lOO

IIS

of each line being in parallel with each other, A

while thevlimbs of the two connected lines are in series. The above expression, as employed in the claims, is intended to comprehend both or either of these structures.

Having described my invention, what I claim as new, and desire to secure by Letters Patent, is-

1.v` The combination with a pair of telephone-lines, each having two limbs, of a third conductor connected with each telephone-line u at the substation, and a source of electricity at the central station adapted to be connected to send current over a circuit including in` series said third conductor and the two tele-` phone-lines, substantially as described.

2. The combination with a pair of telephone-lines'each having two limbs comprising a metallic talking-circuit, of a charging-cirv from, one line of each connected pair beingy connected with one pole of said battery while the other line of `the `pair is connected with the opposite pole of the battery, said battery being adapted to send current over the connected lines in series, an induction or repeating coil adapted to be interposed between the` two connected lines and 'a retardation or imp pedance coil connected between each telephone-line and the battery, substantially as described.

4:. In combination, a plurality of telephonef lines, a plurality of cord connectors for connecting the lines together and a common battery or source of current, one terminal of each cord connector heilig connected with one pole of the battery while the other terminal is connected wit-l1 the opposite pole ot' the battery, said source of current being adapted to send current overthe two connected lines in series,

substantially a's described.

5. In combination a plurality of telephonelines, a plurality ofcord connectors for connecting the lines together, an induction or repeating coil interposed `between the ter` minals thereof, a com thon battery or source of current, one terminal of each cord connector being connected with one pole of the battery while the other terminal is connected with the opposite pole of the battery, said battery being adapted to send current over the two connected lines in series,substantially as described.

G. In combination, aplurality of telephonelines, a plurality of cord connectors for connecting the lines together, an induction or repeati n g coil interposed between the terminals thereof', a common battery or source of current adapted to send current over the two connected lines in series, one terminal of each cord connector being connected with one pole of the battery while the other terminal is connected with the opposite pole of the battery, and a retardation or impedance coil between each terminal and the battery, substantially as described.

7. In combination, aplurality of telephonelines each having a metallic talking-circuit and a transmitter-charging circuit comprising one or both limbs of the talking-circuit and aA third conductor,a plurality of cord connectors for connecting the lines together, an induc-` tion orimpedance coil interposed between the terminals thereof, a common battery or source oi' cu r-rent adapted to send current over the two connected lines in series, one terminal of each cord connector being connected with one pole of the battery while the other terminal is connected with the other `pole of the battery,'anda retardation or impedance coil between each of said terminals and the battery, substantially as described.

8. In combination, a plurality of telephonelines each `having a metallic talking-circuit and atransmitter-cha rging circuit comprising one or both limbs ot the talking-circuit and a third conductor,a pluralityof cord connectors for connecting the l-ines together, an induetion or repeating coil interposed between the terminals thereof, a com mon battery or source of current adapted to send current over the two connected lines in series, one terminal of each cord connector being connected with one pole oi' the battery while the other terminal is connected with the other pole of the battery, and a clearing-out annunciator between each of said terminals and the battery and possessing retardation or im pedance,substantially as described.

9. In combination, a plurality of telephonelines having a metallic talkingcircuit and a transmitter-charging circuit comprising one or both limbs of the talking-circuit of each line and a third conduct-or, a plurality of cord connectors for connecting the lines together, induction or repeating coils interposed between the terminals thereof, the electrical centers of the windingsof the induction or repeating coils being connect-ed respectively with the opposite poles of a charging-battery or source of current, and a retardation or impedance coil connected in circuit between said windings and the battery, substantially as described.

lO. The combination with a pair of telephone-lines, each having two limbs, ot' a third conductor connected with each telephone-line at the substation, a source of electricity, and connecting devices at the central station for connecting said source of electricity to send current over a circuit including in series said third conductor and the two telephone-lines, substantially as described.

l1. The combination with a plurality of telephone-lines, each having two limbs, of a third conductorv connected with each telephone-line at the substation, connecting devices for connecting the telephone-lines in pairs, and a source of electricity common to the plurality of telephone-lines and adapted to be connected to send current over a circuit including in series said third conductor and the two telephone-lines of a connected pair, the several connected pairs of lines being in parallel with each other, substantially as described.

12. The combination with a pair of telephone-lines, each having two limbs comprising a metallic talking-circuit, of a third con- ICO IIO

IIS

ductor connected with each line at the sub1 station, telephone apparatus associated with said metallic circuit to send talking-currents thereover, and a charging source of electricity: adapted to be connected to send currents over a circuit including in series said third con` ductor and thetwo telephone-lines, substantially as described.

13. The combination with a pair of telephone-lines, each having two limbs, of a third conductor, connected with-said telephoneli-nes at the substation, asource of electricity adapted to be connected to send currents over a circuit including in series said third conductor and the two telephone-lines, a microphonev and primary of lan induction-coil included in said series circuit, and the secondary of an induction-coil included in circuit with the two limbs,substantially as described.

14. The combination with a pair of telephone-lines, each having two limbs, of athird conductor c onnected with said telephonelines at the substation, a source of electricity adapted to be connected to send currentover a circuit including in series said conductor and the two telephone-lines, a microphone and the primary of an induction-coil in par-y allel with each other and included in said series circuit and the secondary of an induction-coil` in circuit with the two limbs, substantially as described.

l5. The combination with the two telephone-lines, eachhaving two limbs, of athird telephone-lines, each having two limbs, of a' third conductor connected with said telephone-lines at the substations, connecting devices for uniting said telephone-lines in pairs,- a source of electricity common to the plu# rality of telephone-lines and adapted to send current over a circuit including in series said third conductor and the two lines ofa connected pair, and means for preventing the variations of current on one of said connected pairs from affecting the other connected pairs, substantially as described.

. `117. The combination with aplurality of telephone-lines, each having two limbs, of a third conductor connected with said telephonelines at the substations, means'for connecting the same in pairs, a source of electricity adapted to be connected to send current over a circuit including in series said third conductor andthe two lines of a connected pair, the several connected pairs being in parallel witheach'ot'her, and a resistanceinterposed between each line and vsaid sourceof electricity, substantially as described. y

18, The combina-tion with a plurality of telephone-lines, each having two limbs, of a third conductor vconnected with said. telephone-lines at the s'ubstations', means for con- `necting the samein pairs, a source of electricity adapted to be connected to sendl cur- 4rent over a circuit'including in series `said third conductor and the two lines of al connected pair, the severalconnected pairs being lin parallel with eachother, anda retardation or impedance coil. interposed between each line vand said source of electricity, substantially as described.` l

19. The combination with a plurality of IleSSeS.

WILLIAM W. DEAN. Witnesses:

W. OLYDE JONES, PERcY C..G1LL. 

